In conventional conveyor systems, particularly systems for transporting bulky aggregates such as coal, iron ore, and the like, the feed material is subject to considerable spillage at the feed point(s) of the conveyor system where the hopper is designed to deposit the particulate material on the conveyor belts. The hopper normally discharges the particulate material onto a horizontal or inclined segment of the conveyor belt system at the feed point(s), and in order to limit the spillage of material, flexible skirts or skirtboards are provided to bridge the gap between the lower end of the hopper and the conveyor surface. In view of the abrasive nature of the material normally conveyed, and the need for the conveyor belts to travel under the skirts in contact with the flexible edges of the skirt, the skirts are subject to considerable wear and there is ample opportunity for the particulate material to displace the skirts and spill out over the edges of the conveyor at the feed end. To reduce the tendency for spillage, wear liners have been mounted on the inside walls of the hopper to direct the particulate material toward the center of the conveyor belt.
Not only is there a tendency for the particulate material being conveyed to spill out between the skirt and the conveyor, at the feed hopper or chute there is considerable dust and fine material which tends to migrate into the operating parts at the feed end of the conveyor and cause problems with the proper operation of such parts.
Even with the use of a liner on the inner surface of the hopper walls, there is still a tendency for the particulate material to gravitate outwardly under the liner and the lower edge of the hopper wall, and to foul the roller mechanisms or other devices supporting the belt. To overcome this, it has been the practice to provide an adjustable skirt on the outside of the hopper wall positioned to bridge the gap between the lower edge of the hopper wall and the conveyor belt. Such aprons or skirts are normally mounted so as to be adjustable and/or replaceable to accommodate for wear and damage to the skirts by the conveyor belt and the particulate material.
Efforts to minimize wear, for example by increasing the durometer of the skirt material or increasing the pressure by which the skirt material bears against the conveyor belt, tend to score the conveyor belts and wear grooves into the conveyor belt where the conveyor belt is contacted by the skirt. Resilient mounting of the skirt has not been a satisfactory solution.
Skirtboards between the lower edge of the hopper and the conveyor are shown in various prior patents. In most cases, the skirtboard is mounted on the hopper wall for vertical adjustment, and the operation of the conveyor must be arrested when the skirtboard is adjusted to compensate for wear or damage. In the Stahura U.S. Pat. No. 4,236,628, there is disclosed an adjustable mounting for the skirtboard which affords adjustment of the skirtboard without the need for stopping the conveyor. In all of the prior art devices, the adjusting mechanism for the skirtboard tends to become clogged with dust or other foreign matter from the particulate material being fed through the hopper channel, and the adjustability of the skirtboard is impaired.
The present invention is an improvement upon the skirt-mounting arrangement of the type shown in U.S. Pat. No. 4,236,628. A commercial embodiment of this invention has been made available by Martin Engineering Company under the trademark "TRAC-MOUNT" in which the skirtboard is in the form of a series of interengaged rubber blocks which are individually adjustable in metal tracks so that the skirting may conform to the varying profile of the conveyor belt. Such devices are not entirely satisfactory in view of the tendency of the rubber blocks to wear grooves into the conveyor belts and the frequent occurrence of build-up of material causing the blocks to disengage from their tracks and create gaps in the skirting.